This invention relates generally to track formats for computer disk drives.
Disk drive systems store data magnetically, often in multiple disks each having two storage surfaces. Bytes of information are stored on these surfaces as binary ones and zeros. In order to efficiently store and retrieve bytes of information stored on such disks, disk drive controllers need to know locations on the disk where to write data to and read data from the disk. Each location on a disk is identified, therefore, by short segments of site information stored at various locations on the disk surface. Using this site information, the disk drive can accurately store data to, and retrieve data from, desired locations on the disk surfaces.
Data are stored in multiple concentric circular tracks on one or more surfaces of the disk. On each track are spoke areas separated by user data areas. The spoke areas generally include a spoke number field to discriminate one spoke on a track from another. The information in the spoke number field is used to establish a position of the disk relative to magnetic heads in the disk drive that are used to read and write the disk surface. Techniques which have been used to produce a spoke number include providing a whole spoke number in each spoke field to provide a straightforward technique to identify angular position anywhere on the track. Another technique uses a portion of the full spoke number, such as an N number of LSB""s of the spoke number, in each spoke field. This arrangement also requires that certain spoke fields have a uniquely formatted index spoke in order to fully identify the position of any spoke field when angular position context is lost in the disk drive. The provision of uniquely formatted index spokes are needed since using an N number of bits in the spoke field will result in an ambiguous identification of a spoke beyond a range of 2n spokes.
According to an aspect of the invention, a disk for a disk drive system includes a disk having a track format region including a spoke field region, said spoke field region having a single binary bit to identify angular position of a track with respect to disk head of the disk drive system.
According to an additional aspect of the invention, a disk drive system includes a disk drive and a disk operatively associated with the disk drive, said disk having a plurality of track format regions, each track format region including a spoke field region, said spoke field region having a single binary bit to identify angular position of a track on the disk with respect to the at least one disk head of the disk drive system.
According to a still further aspect of the invention, a servowriter for a disk drive includes a pseudorandom sequence generator to produce a single binary bit of a spoke field region for each of a plurality of track format regions of a disk.
According to a still further aspect of the invention, a method of writing servo areas of a track format includes generating a pseudorandom sequence of vectors and writing the LSB of each vector of the pseudorandom sequence to corresponding spoke number fields of the disk.
One or more advantage may be provided by the invention. The single bit spoke number field 50d is a single bit field which is used to provide an unambiguous identification of angular position. The single bit spoke number field can provide the functions of the conventional spoke number field and the conventional head/surface field with a single bit. The single bit spoke number field uses a single bit to represent the angular position of the disk surface relative to the disk heads. Each of the spoke number fields is populated with a single bit that assumes a binary value of 0 or 1. Each spoke bit is generated in a specified manner such that a complete spoke number identification is obtained from reading a few consecutive spoke numbers anywhere on a track.